class DB:
    """数据库验证"""
    def __init__(self, db):
        self.db = db

    def verify(self, sql='SELECT 1;'):
        return self.db.execute_sql(sql)


class MySQL(DB):
    pass


class Oracle(DB):

    def verify(self, sql='select 1 from dual'):
        return self.db.execute_sql(sql)


class Postgres(DB):
    pass


class MSSQL(DB):
    pass


class DB2SQL(DB):
    pass


class Promethus:
    pass
